That said, I doubt humanity spent enough time in caves or other restricted airflow environments for such a response to evolve...
This article about one of the few remaining hunter-gatherer people left, the Hadza, might lead you to question the idea that humans have a "dislike body odor" trait:
> While Hadza have a word for body odor, the men tell me that they prefer their women not to bathe—the longer they go between baths, they say, the more attractive they are. Nduku, my Hadza language teacher, said she sometimes waits months between baths, though she can't understand why her husband wants her that way.
https://www.nationalgeographic.com/magazine/2009/12/hadza/
And this despite the theory that hunter-gatherers are probably even better at smelling than we are: https://www.sciencedaily.com/releases/2018/01/180118142744.h...
The idea of ‘cave man’ is sampling bias because natural caves preserve ancient artifacts which tend to disappear in the open.
Fun fact: We've known since ~1850[1] that we should probably stay below 1000ppm for indoors, but we based the measure back then on body odor :) (It still bugs me that oddly cognitive impairment starts at the same point a body-odor measure from the 1800s put CO2 levels, and I keep wondering if we're seeing confirmation bias in action)
In general, where you end up is based on airflow. To get below 800ppm, you'll probably need to increase outside ventilation to >10dm^3/s.
[1] von Pettenkofer, "Ueber den Luftwechsel in Wohngebaeuden"